1. Field of the Invention
The present invention relates to an electrostatic recording apparatus of the type in which an electrostatic image is recorded by an electrostatic recording head onto a sheet of recording paper as the latter travels between the electrostatic recording head and a roller, and the electrostatic image as recorded is then developed and fixed on the sheet of recording paper, and more particularly to an arrangement for driving the roller.
2. Description of the Prior Art
FIG. 1 shows a typical prior electrostatic recording apparatus. A rolled sheet 1 of recording paper is transported by a pair of transport rollers 2a, 2b so as to travel between an electrostatic recording head 3 and a roller 4, during which time an electrostatic image is formed on the continuous sheet 1 by the electrostatic recording head 3. The continuous sheet 1 with the electrostatic image thereon is caused by a pair of transport rollers 5a, 5b to pass through a cutter 6, and by a pair of transport rollers 7a, 7b to enter a development device 8, in which the electrostatic image is developed into a toner image. The toner image thus developed on the continuous sheet 1 is then fixed by a fixation device 9 . The continuous sheet 1 is thereafter discharged by a pair of discharge rollers 10a, 10b out of the electrostatic recording apparatus. The continuous sheet 1 is cut off at its trailing end by the cutter 6 when electrostatic recording by the electrostatic recording head 3 is completed.
The continuous sheet 1 is pressed against the electrostatic recording head 3 by the roller 4 as the continuous sheet 1 is fed along between the electrostatic recording head 3 and the roller 4 on driven rotation of the latter. When the roller 4 is accidentally driven to rotate with no recording paper present between the electrostatic recording head 3 and the roller 4, electrodes mounted on the electrostatic recording head 3 are liable to become damaged by frictional engagement with the roller 4. To eliminate such a problem, the cutter 6 is located at the downstream side of the electrostatic recording head 3 and the roller 4 with respect to the direction of feed of the continuous sheet 1, so that the continuous sheet 1 is interposed between the roller 4 and the electrostatic recording head 3 at all times to protect the electrodes on the electrostatic recording head 3 against contact with the roller 4. Such an arrangement however allows only a continuous roll of recording paper to be used in the electrostatic recording apparatus, and precut sheets of recording paper cannot be employed.
With the prior electrostatic recording apparatus, a portion of the continuous recording sheet which is coextensive with a distance W between the electrostatic recording head 3 and the cutter 6 becomes useless in the next cycle of copying operation since no electrostatic image whatsoever can be formed on such a sheet portion. The blank portion of the recording sheet must be severed by the cutter 6, which is required to be actuated to perform such paper cutting in a complex controlled operation.
It is accordingly an object of the present invention to provide an electrostatic recording apparatus having an electrostatic recording head which is protected against unwanted damage due to frictional contact with an associated roller.
Another object of the present invention is to provide an electrostatic recording apparatus capable of preventing generation of waste portions of recording paper, and recording electrostatic images on a roll of recording paper or on precut sheets of recording paper.
Still another object of the present invention is to provide an electrostatic recording apparatus which can print images on a roll of recording paper fully over its entire surface without giving rise to waste portions of the recording paper.
A still further object of the present invention is to provide an electrostatic recording apparatus which can record electrostatic images on sheets of recording paper having a variety of sizes.